Resin transfer molding has been disclosed in a number of publications and patents including, for example, U.S. Pat. Nos. 4,568,057 and 4,608,453 both issued to Richard B. Freeman. The latter patent discloses metallic elements acting as a shield disposed between layers of fiber.
Generally, when a fiberglass structure is formed using the resin transfer molding process, the fiber material is disposed in a mold including upper and lower mold pieces. With the fiber material between the mold, resin is injected into the fiber material while the fiber material is under heat and pressure. After the resin has been injected the formed fiber product is allowed to cool.
Fiberglass structures have been used recently in the development of many automotive components including, for example, doors. In cases involving automotive doors, metal inserts or reinforcements must be used to provide strong structures, to permit the connection thereto of such items as door handles, hinges and other components which must be mounted to the door after the doors have been initially formed.
In the formation of the automotive component, for example, layers of fiber are employed which are impregnated with resin. When metal inserts or reinforcements are disposted between the layers, concentration will exist at the edges of the metal insert which tend to lead to inter-laminar shear failure. With a resin molded structure, the metal reinforcement is generally placed into the mold along with dry unimpregnated fiber reinforcement. When one of the configurations of a metallic reinforcements of the present invention is used, the potential inter-laminar shear failure is prevented or minimized.